The ongoing development of micro-processor technology has increased the operation speed of micro-processors to the present level of tens of Gb/s. However, limited by electrical connections, they cannot keep up with similarly high data speeds. To overcome the limitations of electrical connections, optical interconnections have been proposed. Since optical interconnections between chips or boards enable high-speed signal transmission, high-density wiring lines, and low power consumption, they further enhance the signal processing ability of large-scale computers and next-generation mobile communication systems.
To effectively transmit optical signals, it is essential that passive optical elements as well as active optical elements, for example, an optical interconnection block and an optical waveguide, are mounted or connected in such a manner that optical power can be minimized. Optical signals applied to an optical PCB are transmitted through the following process. The direction of an optical signal emitted from an optical transmitter element, for example, semiconductor laser, is deflected 90 degrees in an optical interconnection block so as to pass through an optical waveguide formed of a polymer or silica fiber installed in the optical PCB. Then, the optical signal is delivered through an optical interconnection block to an optical receiver element, for example, a photodiode.
Korean Patent Laid-open Publication Nos. 10-2004-0089014 and 10-0575951 shown in FIGS. 1 and 2 disclose a method of passively connecting optical elements for high-precision alignment by using guide pins 202. In such a method, high optical efficiency can be achieved and an optical interconnection system can be easily manufactured.
However, a separate PCB 203 for mounting the optical transmitter and/or receiver modules 205 to 208 is needed, and noise may occur in a line for transmitting electrical signals between the separate PCB 203 and an optical PCB 204. Further, during a process of connecting the optical PCB 204 to optical interconnection blocks 101, an alignment error inevitably occurs between the light emitting and receiving elements 205 and 206 and the optical interconnection blocks 101, and between the optical interconnection blocks 101 and an optical waveguide 210 of the optical PCB 204. In this case, optical loss occurs.
Further, since the guide pins 202 are used, the optical elements may come off due to vibration or deform due to temperature change when the optical interconnection system is used. Therefore, it is impossible to guarantee stable operation of the system for a long time. Furthermore, the connection operation between the optical elements through the guide pins 202 is not easy to perform, and the optical fiber within the optical interconnection blocks 101 may be damaged during the operation.